溶胶凝胶法制备的Cu/SiO2催化剂及其催化草酸二甲酯加氢反应

采用溶胶凝胶法制备了用于草酸二甲酯加氢合成乙二醇的Cu/SiO2催化剂,在优化的反应条件下,当催化剂中Cu含量为15%～25%时,草酸二甲酯转化率和乙二醇选择性分别达到99.9%和95.0%.通过N2吸附-脱附、透射电镜、X射线衍射、氢气程序升温还原、N2O滴定法和X射线光电子能谱等手段对各Cu/SiO2催化剂进行了表...     

Sn改性的Ru/H-CMK-3催化剂的制备及其肉桂醛选择性加氢性能的研究

用浸渍-原位还原法制备了Ru-Sn/H-CMK-3催化剂. 以肉桂醛选择性加氢制备肉桂醇为探针反应. 详细研究了催化剂的制备及反应条件对肉桂醛选择性加氢性能的影响. 采用X 射线粉末衍射(XRD)、比表面积(BET)、X光电子能谱(XPS)、透射电镜(TEM)等手段对催化剂结构和性质进行了表征. 结果表明, 介孔CMK-3碳材料能够更好地分散活性物种. 添加适量的Sn(IV)有利于Ru处于电子富集状态. 催化剂的主要活性物种是纳米Ru粒子, Ru和Sn之间的相互作用更加有利于C＝O的活化. 同时, 反应温度和反应压力等条件的变化对肉桂醛选择性加氢制备肉桂醇反应也具有较大的影响.     

Application of Sol-Gel Method to Preparation of Ultra-Uniform Co-Based Catalysts for Fischer-Tropsch Reaction

Uniformly dispersed Co/SiO₂ catalysts (10–60 wt% on metal basis) were prepared by the sol-gel method, and used for the Fischer-Tropsch (F-T) synthesis in slurry phase at 503 K and 1 MPa in a flow of synthesis gas (H₂/CO = 2/1, W/F = 10 g-catal·h/mol). The catalysts were characterized by temperature-programmed reduction (TPR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and chemisorption. Although CO conversion over the unpromoted catalysts prepared by the sol-gel method was lower than the conventional catalysts prepared by impregnation, the catalytic activity of the former catalysts was more stable than the latter catalysts. The conversion was improved drastically, when 0.01–1 wt% of Ir or Ru (on metal basis) was added to the catalysts prepared by the sol-gel method. The TPR and XPS spectra and the H₂ chemisorption revealed that the noble metal addition was responsible for the reduction of Co particles in the catalysts. It is supposed that the durability of the promoted catalysts prepared by the sol-gel method was ascribed to the high dispersion of Co particles stabilized on the catalyst surface.     

Effects of the preparation methods on the properties of Ni-La2O3-SiO2 catalysts for m -dinitrobenzene hydrogenation

Ni-La₂O₃-SiO₂ catalysts were prepared by wetness impregnation and sol-gel method followed by conventional drying and supercritical drying, respectively. Their physico-chemical properties and activity for the hydrogenation of m-dinitrobenzene to m-phenylenediamine were investigated by BET, XRD, TPR, H₂-TPD and activity tests. The results showed that the structural and catalytic properties of the Ni-La₂O₃-SiO₂ catalysts obviously depended on the preparation method and the drying mode. The catalyst prepared by the sol-gel method in combination with conventional drying exhibited the highest catalytic activity among the catalysts tested, attributable to its well-dispersed nickel particles and larger active nickel surface area.     

Ru/ZSM-5催化葡萄糖选择性加氢制备山梨醇(英)

采用无有机模板剂一步法制备了Ru/ZSM-5催化剂,利用X射线衍射、N₂吸附-脱附、NH₃-程序升温脱附和CO₂-程序升温脱附、扫描电镜和透射电镜等方法对催化剂进行了表征.考察了反应温度、钌负载量和催化剂重复利用等因素对Ru/ZSM-5上葡萄糖加氢反应性能的影响,并与浸渍法制备的Ru/ZSM-5催化剂进行了对比.结果表明,与传统浸渍法相比,一步法制备的Ru/ZSM-5催化剂钌粒子具有更高的分散性和稳定性.在120℃和4 MPa的温和反应条件下,葡萄糖接近完全转化,山梨醇选择性高达99.2%,催化剂可重复利用5次,仍保持较高活性.     

Ruthenium-tin sol-gel catalysts: effect of the preparation and tin precursor influence

The influence of the synthesis route and the chemical nature of tin precursors on the catalytic properties of supported sol-gel Ru-Sn/SiO₂ catalysts were studied. It was demonstrated that introduction of tin afforded better selectivities than a monometallic sol-gel catalyst in the liquid-phase hydrogenation of cinnamaldehyde; however, the chemical nature of the tin precursor did not influence the catalyst performance. Sol-gel catalyst properties depended significantly upon the preparation method used and on the activation temperature. The selectivity to unsaturated alcohol increased with conversion, which is indicative of the in-situ creation of active sites selective in the carbonyl bond hydrogenation.     

Structure of Pd/SiO2 sol-gel and impregnated catalysts

Palladium catalysts were prepared by sol-gel and impregnation techniques both in acid and basic media. The sol-gel catalysts resulted in larger PdO crystallites than the impregnated catalysts. In both preparation methods, an acid medium promoted the formation of small metal crystallites which provided catalytic activity. A stronger metal-support interaction was found in sol-gel catalysts synthesized from a square planar palladium complex. Deactivation results in phenylacetylene hydrogenation have been attributed to palladium hydrate formation or to deposition of carbonaceous compounds. The preparation mode determined the contribution of each deactivating reaction.     

Development of 4,4'-substituted-XylBINAP ligands for highly enantioselective hydrogenation of ketones

[reaction: see text] A family of 4,4'-substituted-xylBINAPs was synthesized in multistep sequences and characterized by NMR spectroscopy and mass spectrometry. Ru(diphosphine)(diamine)Cl(2) complexes based on these 4,4'-substituted-xylBINAPs and chiral diamines (DPEN and DAIPEN) were synthesized by treatment of [(benzene)RuCl(2)](2) with 4,4'-substituted-xylBINAP followed by chiral diamine, and characterized by (1)H and (31)P NMR spectroscopy and mass spectrometry. These Ru complexes were used for asymmetric hydrogenation of aromatic ketones in a highly enantioselective manner with complete conversion. With 0.1% catalyst loading, complete conversion and enantioselectivity greater than 99% were obtained for most of the aromatic ketones examined. These Ru catalysts thus gave the highest ee for asymmetric hydrogenation of aromatic ketones among all of the catalysts reported in the literature. A single-crystal X-ray diffraction study of Ru[(R)-L(4)()][(R,R)-DPEN]Cl(2) indicated that the 4-methyl group of the naphthyl ring and the methyl groups of the two xylyl moieties form a fence on the opposite side of the DPEN ligand of the Ru center. These three methyl groups will have significant repulsive interactions with the bulky aryl ring of the hydrogen-bonded aromatic ketone in the disfavored transition state. These results support our hypothesis of combining dual modes of enantiocontrol (i.e., the substituents on 4,4'-positions of the binaphthyl framework and the methyl groups on the bis(xylyl)phosphino moieties) to achieve higher stereoselectivity in the hydrogenation of aromatic ketones.     

Ru-Zn催化剂在苯选择加氢制环己烯反应中的粒径效应

采用共沉淀法制备了水溶性聚合物修饰的苯选择加氢制环己烯Ru-Zn催化剂, 并用X射线衍射、 透射电镜、 X射线能量色散谱、 X射线光电子能谱和氮气物理吸附等对加氢后催化剂进行了表征. 结果表明, 水溶性聚合物的种类和聚乙二醇-20000(PEG-20000)的用量对Ru-Zn催化剂微晶尺寸有显著影响. 在ZnSO₄存在下, 随着Ru-Zn催化剂Ru微晶尺寸增加, 苯转化率降低, 环己烯最高收率则呈火山型变化趋势. 用0.4 g PEG-20000修饰的Ru-Zn催化剂[m(PEG-20000)∶m(Ru)=0.2]Ru的微晶尺寸为4.8 nm, 环己烯最高收率为62.2%. Ru微晶尺寸影响催化剂表面的Zn/Ru原子比, 进而影响Ru-Zn催化剂性能.     

ZrO_2负载Pt催化巴豆醛选择性加氢

以高比表面积ZrO2为载体,采用浸渍法制备了负载型Pt催化剂,应用于常压下气相巴豆醛加氢反应,考察了Pt负载量和H2还原温度等对巴豆醛选择性加氢性能的影响.实验结果表明,Pt负载量(质量分数)为3%的3Pt/ZrO2催化剂经500℃还原后,具有较高的巴豆醛选择性加氢性能:巴豆醛转化率为27%,巴豆醇的选择性为55%.X射线粉末衍射(XRD)分析,CO化学吸附,NH3程序升温脱附(NH3-TPD)表征结果表明Pt/ZrO2催化剂上Lewis强酸中心和适宜的Pt颗粒(约为8nm)有利于巴豆醛选择性加氢生成巴豆醇.     

Cooperation between Pt and Ru on RuPt/AC bimetallic catalyst in the hydrogenation of phthalates

RuPt/AC bimetallic catalysts were pre pared by two-step incipient impregnation method and evaluated in the hydrogenation of phthalates.According to the characterization results,well dispersed Ru Pt bimetallic nanoparticles were formed on the catalyst,and the strong interaction between the two metals resulted in the formation of RuPt alloy.It was found that Ru can donate electrons to Pt on RuPt alloy nanoparticles,leading to the formation of electron-deficient Ru which significantly promotes the hydrogenation rate of dioctyl phthalate and improves the selectivity of dioctyl di-2-ethylhexylcyclohexane-1,4-dicarboxylate by accelerating the further hydrogenation of intermediate products.The bimetallic RuPt catalyst also presented excellent stability and versatility in the hydrogenation of phthalates,demonstrating its prospective future in the hydrogenation of aromatic ring contained compounds.     

钌锡比对Ru-Ir-Sn氧化物阳极涂层性能的影响

应用溶胶凝胶法制备了不同钌锡摩尔比氧化物阳极涂层.SEM,EDX,强化电解寿命,循环伏安和电化学阻抗等测试表明,钌锡摩尔比对阳极涂层的表面形貌以及电化学性能有很大影响.随着钌含量的增加涂层的强化电解寿命呈先增加后降低变化,析氯电位呈先降低后增加;电流效率呈先增加后降低,与其对应的循环伏安电量以及双电层电容值亦呈先增加后减小变化.     

葡萄糖加氢用Ru/活性炭催化剂: 改性方法对活性炭表面性能的影响

分别采用超临界甲醇流体、浓硝酸氧化、浓硝酸结合超临界甲醇流体等不同手段对椰壳活性炭进行了表面处理,用N2物理吸附、Boehm滴定、X光电子能谱仪(XPS)、电感耦合等离子原子发射光谱分析(ICP)、透射电镜(TEM)等手段研究了处理方法对活性炭表面孔结构及表面基团的影响;并以活性炭为载体,三氯化钌为活性前驱体,采用等容水浸渍法制备了钌炭催化剂,以葡萄糖加氢生产山梨醇为模型反应对制备的钌基催化剂的催化活性进行了评价.结果表明:各种处理方法对活性炭的比表面、孔径等孔结构性能影响不大;但超临界甲醇处理活性炭可明显减少活性炭表面含氧酸性基团的含量,尤其是羧基等不稳定基团的含量;而硝酸处理活性炭则可大幅度提高活性炭表面含氧酸性基团的含量,尤其是羧基等不稳定基团的含量增加更大.ICP分析结果表明:超临界甲醇处理活性炭并不改变活性炭样品对钌的吸附量,但硝酸氧化处理活性炭却能明显提高样品对钌的吸附能力.活性炭表面的这些含氧基团虽然有利于钌离子的吸附,但却不利于钌在活性炭表面的分散.由于超临界甲醇流体处理活性炭时的表面反应及萃取作用,可有效清除活性炭表面的不稳定含氧酸性基团,避免还原过程中钌的迁移聚集,使负载钌的分散度提高,有利于增强钌与活性炭间的相互作用,使钌部分缺失电子,钌的结合能升高;可明显提高负载钌炭催化剂葡萄糖催化加氢的活性.     

A novel strategy for heterogenisation of homogeneous and colloidal chiral catalysts and their application in enantioselective reactions

For the heterogenisation of chiral catalysts, a novel method has been developed and applied to different enantioselective reactions. The new heterogenisation method is based on the three-dimensional entrapment of catalysts by electrostatic attraction between a polyelectrolyte and an oppositely charged catalyst. An easy preparation procedure, a simple separation and a good retention of the active metal in the polymeric material and a high long-term stability of the entrapped catalyst are the significant features of this new heterogenisation method. Applying these entrapped catalysts in the hydroformylation of vinyl acetate, an enantiomeric excess (ee) of 39% could be obtained with a rhodium diphosphine complex. The activities and selectivities in the hydrogenation of dimethyl itaconate have been found to be competitive with homogeneous catalysts. A change in the direction of enantioselectivity has been observed by using entrapped Ru catalysts in different solvents. For the entrapment of chirally stabilised Pt-colloids used in the enantioselective hydrogenation of ethyl pyruvate, different polyanions have been found to be suitable. A constant enantioselectivity and a good activity during 25 hydrogenation cycles were obtained employing alginate-entrapped Pt-colloids.     

Catalytic conversion of lactic acid into propylene glycol over various metals supported on silica

Catalytic hydrogenation of lactic acid to propylene glycol was performed over various metals (Ag, Co, Cu, Ni, Pt, and Ru) supported on silica prepared by an incipient wetness impregnation method. The loading amount of each metal was 5 wt%. Crystallinity of the synthesized catalysts was investigated by X-ray diffraction (XRD), and the BET method was utilized to examine the surface area. Pore volume and pore size of catalysts were determined using BJH analysis of the N₂ adsorption isotherm. Particle sizes of various metals were determined from transmission electron microscopy (TEM) images. The catalytic activity was found to be strongly dependent on the supported metal. Among catalysts tested, Ru/SiO₂ showed the highest propylene glycol yield. The yield of propylene glycol increased with pressure, and the highest yield was achieved at 130 °C.     

制备条件对Pd催化剂上C3H6选择性还原NO性能的影响

采用浸渍法和溶胶凝胶法,制备了Pd/AI2O3和Pd/AI2O3-CeO2样品,并测定了不同温度焙烧后催化剂的物相、比表面积及对丙烯选择性还原NO的活性。对于Pd/AI2O3,随着焙烧温度的提高,其NO的最大转化率逐渐下降,对应的反应温度在290－310℃左右,而溶胶凝胶法制备的样品活性略高于浸渍法制备的样品;对于Pd/AI2O3-CeO2,经600℃焙烧后,其NO的最大转化率为22％,900℃焙烧的催化剂样品上NO的最大转化率达到40％左右,对应的反应温度也逐渐下降,说明活性随焙烧温度的提高而明显提高,溶胶凝胶法和浸渍法制备的样品结果很接近,浸渍法制备了若干不同Pd负载量的Pd/AI2O3样品,活性测定的结果表明,Pd含量在0．5％左右的催化剂样品中具有最高的活性。     

苯中硫在Ni/ZnO催化剂上加氢吸附脱除的研究

比较了浸渍法与共沉淀法制备的Ni/ZnO催化剂对芳烃原料的深度脱硫活性和选择性,并采用H₂-TPR、XRD和BET等手段对催化剂进行了表征。结果表明,NiO与载体ZnO之间的相互作用程度对催化剂的性能有很大影响。与ZnO相互作用较弱的游离态NiO还原后生成的Ni⁰,导致苯加氢生成环己烷;与ZnO相互作用较强的NiO还原后生成的Ni⁰具有脱硫能力但不是苯加氢活性中心。共沉淀法制备的催化剂由于NiO与载体相互作用较强,游离态NiO较少,且比表面积相对较大,因而具有较高的活性和选择性。同时发现,还原温度对催化剂的性能具有很大影响,在400℃还原时开始出现Ni_xZn_y合金,且随着还原温度的升高,晶粒长大,比表面积降低,导致催化剂活性降低。Sn助剂的加入能增加NiO与载体的相互作用,抑制游离态的NiO生成,从而减少苯的损失。     

CO2加氢合成二甲醚的催化剂的制备

先采用均匀沉淀法制备出CuO—ZnO催化剂,然后以CuO—ZnO催化剂作为晶核采用水热合成法制备出CuO—ZnO／HZSM-5（氢型ZSM-5分子筛）复合催化剂．利用X射线衍射和氨程序升温脱附手段对复合催化剂进行表征,并应用于CO2催化加氢合成二甲醚的反应．研究结果表明,在相同的反应条件下,这种CuO—ZnO／HZSM-5复合催化剂与采用物理混合法制备出的复合催化剂相比具有更好的催化效果,不但提高了CO2的转化率、二甲醚的选择性以及二甲醚和甲醇的总选择性,同时还改善了催化剂的稳定性．     

STUDIES ON THE HYDROGENATION OF METHYL ACRYLATE CATALYZED BY Pd/DVB CROSSLINKED POLY-(N-VINYL PYRROLIDONE)

Many kinds of dispersed Pd (0) supported on cross-linked poly (N-vinyl pyrrolidone) were prepared and characterized by IR and X-ray diffraction. Their hydrogenation properties of methyl acrylate have been examined. Experimental results indicate that the hydrogenation rate will reach a maximum as the degree of crosslinking increases to a certain point. The catalytic activity of the catalysts is closely related to the preparation condition and the particle size of Pd of the catalysts. Some other factors which affect the catalytic properties have also been studied.     

Studies on the Simultaneous Synthesis of Dimethyl Carbonate and Poly（ethylene terephthalate）： I. Catalytic Activity of Metal Acetate in Transesterification of Ethylene Carbonate with Dimethyl Terephthalate

Dimethyl carbonate (DMC) is a new building block of organic synthesis, as an environmentally benign compound and unique intermediate, it has been attracted much attention. Among the various methods for synthesizing DMC, transesterification of ethylene car…